1. Field of the Invention
This invention relates generally to tools, and more particularly to earth-drilling augers used for boring through particulate material, such as soil.
2. Description of the Related Art
Forming a hole in particulate material, such as soil or sand, especially under a surface structure, such as a sidewalk or a building foundation, is commonly effected by a screw-like tool called an auger, which progressively bores or drills into the material. The typical auger has a cutting blade at the distal end of a helical flight that is mounted to an axle. The axle extends longitudinally away from the user, or a rotatable machine, and defines an axis of rotation for the auger's flights. The user rotates the auger, either by hand, or more preferably by machine, such as a drill. As the auger rotates, it removes particulate to form a hole, and conveys the particulate away from the hole by the action of the flights. The auger progressively forms the hole deeper and deeper as it cuts further and conveys particulate away. In some prior art references, additional sections of helically flighted axles can be coupled to the auger.
Some prior art augers and drilling tools that are designed for drilling into compacted earth, such as clay, combine pressurized air and working fluid with the auger for continuously loosening debris from the hole. The fluid and debris are channeled into an escape route sub-assembly system, which is typically a longitudinal hole through the axle. In this way, the hole is regularly flushed and kept relatively clean to enable the inner surface of the hole to be dissociated by the drilling action. However, such prior art drilling tools are bulky and awkward due to the attached pneumatic and hydraulic hoses. Thus, such devices are difficult to maneuver and operate, especially when they are used in narrow spaces. In addition, the escape route sub-assembly system can become clogged with debris, which can damage the tool and delay the progress. Also, fluid can leak from the escape route and soak the surrounding earth, and surface structures can be damaged by, or lose support from, that surrounding earth.
Some augers have been made with various types of fasteners for linking flighted modular sections together in series in order to bore a hole to a certain depth. Augers have also been formed with various cutting blades designed for enhancing the performance of the auger. For example, augers have been designed to be compact and portable in order to be transported and used to drill a hole in ice for ice fishing.
A more significant design in prior art augers involves a limitation to the distance that a helical flight extends along an axle. For example, U.S. Pat. No. 2,221,680 to Parrish teaches an auger having a discontinuous flight attached to the outer surface of the drilling axle. Sections of the flight have been removed from the drilling stem in order to reduce friction that is generated by the rotating land, which is the peripheral edge of the flight, contacting the newly formed sidewall of the hole. The frictional force resisting the rotation of the auger is reduced along the auger.
The prior art augers are not completely satisfactory for hole-forming operations, especially where the hole is to be substantially horizontal. An auger is needed with features designed to overcome the deficiencies that have been described.